Hydrocracking of naphtha

ABSTRACT

A COMPOSITION COMPRISING A SMALL QUANTITY OF PALLADIUM, GENERALLY BETWEEN 0.05 AND 5.0 WEIGHT PERCENT PALLADIUM, DEPOSITED ON A CHELATED HYDROGEN FORM OF ZEIOLITE Y. A METHOD OF HYDROCRACKING NAPHTHA TO LPG WHICH COMPRISES CONTACTING A NAPHTHA CHARGE UNDER HYDROCRACKING CONDITIONS WITH THE AFORENOTED CATALYST.

United States Patent Ofice 3,579,434 Patented May 18, 1971 3,579,434 HYDROCRACKING F NAPHTHA Robert B. Smith, Pitmau, and Barton W. Rope, Mullica Hill, N.J., assignors to Mobil Oil Corporation N0 Drawing. Filed July 2, 1968, Ser. No. 741,867 Int. Cl. Cg 13/02, 13/10 US. Cl. 208-111 2 Claims ABSTRACT OF THE DISCLOSURE A composition comprising a small quantity of palladium, generally between 0.05 and 5.0 weight percent palladium, deposited on a chelated hydrogen form of zeolite Y. A method of hydrocracking naphtha to LPG which comprises contacting a naphtha charge under hydrocracking conditions with the aforenoted catalyst.

BACKGROUND OF THE INVENTION Field of the invention This invention relates to a catalyst especially useful in the hydrocracking of naphtha to LPG products. This invention also relates to the hydrocracking of naphtha to LPG products whereby these LPG products are produced in high yields.

Description of the prior art Many hydrocracking catalysts have been proposed. These catalysts generally comprise an inorganic oxide containing a hydrogenation component thereon. Naphthas have been known to be hydrocracked under conditions designated moderate and severe as discussed by A. M. Henke, B. J. Schmid and J. R. Strom, Hydrocracking of Naphtha for LPG Production AIChE meeting, Feb. 23, 1963, Houston, Tex.

Platinum impregnated zeolite catalyst such as platinum impregnated zeolite Y in the hydrogen form have been proposed for naphtha hydrocracking. While results of hydrocracking naphtha with such a catalyst provide LPG products, these products are not provided at especially high yields and the catalyst does not perform selectively for the production of LPG products. Thus, it has been a desideratum to provide a catalyst which functions selectively to provide high yields of LPG products from naphtha hydrocracking under moderate conditions.

SUMMARY OF THE INVENTION Broadly, this invention contemplates a composition comprising between 0.05 and 5.0 weight percent palladium deposited on a chelated hydrogen form of zeolite Y.

In another embodiment, this invention contemplates a method for hydrocracking a naphtha charge which comprises contacting said naphtha charge under hydrocracking conditions with a catalyst comprising between 0.05 and 5.0 weight percent palladium deposited on a chelated hydrogen form of Zeolite Y.

DESCRIPTION OF PREFERRED EMBODIMENTS It has now been found that a full range naphtha such as a naphtha from Kuwait stock (Table I) can be converted in high yields to C and C hydrocarbons (LPG) by hydrocracking the naphtha over a catalyst comprising palladium on chelated hydrogen zeolite Y aluminosilicate. The palladium can be present in a small quantity, say, between about 0.05 and 5.0 weight percent. Generally, excellent hydrocracking results are obtained employing between about .2 and 2.5 weight percent palladium, especially about .5 weight percent palladium on the chelated HY aluminosilicate. The significant feature of this development resides in the fact that the activity and selectivity of this catalyst for the production of C and C products are markedly superior to results obtained employing other hydrocracking catalysts containing hydrogenation components thereon in substantially greater quantities. Thus, it has been found that the catalyst of the present invention containing about 0.5 weight percent palladium provides substantially superior naphtha hydrocracking to LPG products when compared with a commercially available silica-alumina catalyst containing 2.5 weight percent platinum. Additionally, the catalyst at the 0.5 weight percent palladium level provides superior results to a chelated hydrogen form of zeolite Y containing 1 weight percent platinum impregnated thereon. These results are obtained by hydrocracking under moderate conditions as no particular process parameters need be employed for hydrocracking naphtha employing the catalyst of the present invention.

Employing the catalyst of this invention, naphtha can be hydrocracked at temperatures between 400 F. and 825 F. using molar ratios of hydrogen to hydrocarbon charge in the range between 2 and 80. The pressure will vary between 10 and 2000 p.s.i.g. and the liquid hourly space velocity can be between 0.1 and 10.

The catalyst of the present invention is prepared by preparing a zeolite Y composition, chelating it and ion exchanging the same into its hydrogen form. Thereafter, the chelated HY composition is impregnated with palladium. Zeolite Y in its sodium form can be prepared according to the method of U.S.P. 3,130,007. The zeolite Y can be chelated employing any suitable chelating agent such as ethylenediaminetetraacetate, citric acid, S-hydroxyquinoline, diethylenetriaminepentaacetic acid, and N-hydroxyethylenediaminetriacetic acid.

The zeolite is chelated to such an extent as to effect removal of at least 2 percent and preferably at least 10 percent of the aluminum from the zeolite Y. No more than about 50 percent of the total aluminum should be removed.

The zeolite is thereafter converted to a hydrogen form by any suitable means such as by exchanging the cations with an ammonium salt to convert it into an ammonium form and thereafter heating it at a temperature of about 250 C. causing evolution of ammonia and conversion of the zeolite to the hydrogen form. Other means for preparing hydrogen zeolite Y are known in the art and these are generally suitable in preparing the catalyst.

The zeolite in its hydrogen form is thereafter treated to incorporate palladium into the structure. The palladium can be deposited on the zeolite by impregnation, exchange or any other suitable means. Suitable impregnating agents include palladous ammine chloride prepared by mixing appropriate amounts of palladium chloride with ammonium hydroxide, palladium nitrate, palladium sulfate and palladium iodide. The impregnating agent can be in the form of an aqueous solution or in the form of an organic solution. In some instances, it is desirable to employ a solvent whose molecules are incapable of entering the pores of the zeolite.

When the catalyst has been impregnated with the impregnating agent, it is dried and calcined at a temperature of between 500 F. and 2000 F. for between 2 and 48 hours.

In order to more fully illustrate the nature of the invention and the manner of practicing the same, the following examples are presented:

EXAMPLE I A palladium on chelated hydrogen form of zeolite Y was made by chelating 2275 grams sodium form of zeolite Y with 442 grams sodium ethylenediaminetetraacetate in 4420 grams of water at 200 F. for 24 hours. The chelated zeolite was thereafter exchanged with an aqueous solution of 10 percent by weight ammonium chloride thereby exchanging a major amount of the sodium cations for ammonium cations. The ammonium form was impregnated with palladium nitrate from a solution of the same in dimethyl sulfoxide. Impregnation was achieved by contacting the ammonium form for 24 hours at 150 C.

In all of the hydrocracking runs, the gas collecting and sampling technique led to the loss of hydrogen from the light gas resulting in an analysis very rich in hydrocarbons. The light gas analyses were therefore adjusted to give a 100% carbon balance between the carbon in the naphtha while stirring with Pd (N09 in a dimethyl sulfoxide charged and the carbon in the sum of products. solution, followed by filtration and wash with dimethyl- From the foregoing, it is seen that the catalyst of the sulfoxide at 150 C. Thereafter, it was air dried for 18 present invention under the moderate hydrocracking conhours at 230 F., pelleted and sized 14 to 25 (Tyler) ditions provides substantially greater yields of LPG prodmesh and then calcined at 1000 F. for hours until it 10 ucts than either Catalyst B or Catalyst C. In fact, the volwas substantially free of moisture. ume percent C and C (LPG) provided by the catalyst of Resultant catalyst was employed for hydrocrackin g the present invention is multiples of the volume percent of Kuwait full-range naphtha which was carried out in a these P ucts provided by Catalysts B and C, notwithcontinuous unit at 2000 p.s.i. hydrogen pressure employing standing that Catalyst C contains twice as much weight approximately 7500 s.c.f. of hydrogen per barrel of 15 percent hydrogenation component and Catalyst B cont ins naphtha on a once-through basis. In the hydrocracking five times the weight percent hydrogenation component. runs reported below, each run was followed by an over- Thus, it appears that the present catalyst is markedly sunight period of catalyst regeneration with hydrogen at perior to either of these catalysts for the production of about 950 F. Conditions of temperature and space veloci- LPG produc y hydrocracking p ty are given in the tables below which compares the cat- The terms and expressions used herein have been used alyst of the present invention, designated Catalyst A, with as terms of description and not of expressions as there acommercially available silica-alumina catalyst containing is no intention in the use of such terms and expressions of 2.5 weight percent platinum, designated Catalyst B, and a excluding any equivalent, or portions thereof, as many chelated hydrogen form of zeolite Y containing 1 weight m difications and departures are contemplated within the percent platinum, designated Catalyst C. Catalyst C was scope of the invention claimed. chelated in the same manner as Catalyst A was chelated. What is claimed is:

1. A method of hydrocracking naphtha to LPG prod- TABLE I ucts which comprises contacting said naphtha under hydrocracking conditions comprising a temperature between properties f Kuwait naphtha 400 F. and 825 F., a molar ratio of hydrogen to hydrocarbon between 2 and 80, a pressure between 10 and 2000 Gravity, API 5 5 P- -gand a q id hourly space velocity between 01 and Aromatics, vol. percent 9.7 10 Wlth a catalyst Comprising n amount of about .5 weight Indanes and tetralins, vol. percent 1.1 P Palladlllm deposited a hydrogen form of zeolite Olefins, vol. percent .4 Y which has undergone previous chelation to eflect resaturates moval f at l ast 2 percent but not more than 50 percent Composition, vol. percent: of aluminum from said zeolite Y.

Isobutane 0.1 A method of y racking naphtha to LPG prodm L6 ucts which comprises contacting said naphtha under hylsopentane 2 drocracking conditions comprising a temperature between n-Pentane 5.4 and 5 F2, a molar ratio of hydrogen to hydroc,+ 89. carbon between 2 and 80, a pressure between 1 and Distillation: 2000 p.s.i.g. and a liquid hourly space velocity between IBP, o 109 0.1 and 10 with a catalyst comprising between about .25 164 and 2.5 weight percent palladium deposited on a hydro- 284 g m of z olite Y which has undergone previous h r 395 tion to cflcct removal of at least 2 percent but not more HP 420 than 50 percent of aluminum from said zeolite Y.

TABLE IL-HYDROCRACKING KUWAIT NAPHTHA (cli ei ghi c h a l y t A 2.6% 65 21%? 1% si/Al. (cheizl i e i t l a algst 0 Example No 1 2 3 4 5 6 7 8 9 10 PSJ. 2,000 2,000 2,000 2,000 2,000 2,000 2,000 2,000 2,000 2,000 H} 011 5.5.1.1) 7,500 7,500 7,500 7,500 7,500 7, 500 7,500 7.500 7,500 7,500 L 87 4.25 4.24 2.17 2.10 2.10 2.17 4.25 4.25 4.24 2.17 Cata1ysttemp., F 039 723 074 590 05s 720 753 404 637 057 Conv.(O5+),vol ercent- 39.1 04.0 69.6 0.5 1. 11.2 as 0.0 15.0 53.2 01-1-02, wt. percent 0.2 2.3 1.5 0.2 0.6 0,1 Propane vol.percent 18.3 40.9 40.3 0.3 1.0 7.5 4.8 0.4 6.6 16.8 Iso-butahe vol. percent 34.5 30.3 39.0 0.8 2.8 11.2 8.0 0.9 16.8 29.1 n-Butane 1151. percent... 11.2 23.4 25.4 0.0 1.8 7.5 0.5 1.1 0.3 13.9 05s, v01. percent 27.0 20.3 17.3 7.4 0.4 19.2 17.5 0.8 21.3 11.0

i$1lfiii1 5019 "'f' 30. 4 09.' 2 98:4 2818 9112 90. 1 85.0 45.5

References Cited UNITED STATES PATENTS 3,265,610 8/ 1966 Lavergne et al 208111 3,385,782 5/1968 Buss 2081 11 3,442,795 5/ 1969 Kerr et al. 208

DELBERT E. GANT Z, Primary Examiner R. M. BRUSKIN, Assistant Examiner U.S. Cl. X.R. 

